SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '68a2eaa20e3323d84f1cae00c2f498a0047d33dd83b75867608c71031a261752' 
  AND token = 'AGqjseaQwXTvv5SpMbv4xYzcO9KYQj150VAEQ66QKXE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}